Before this fix, the performance schema tables were defined in UPPERCASE.
This was incompatible with the lowercase_table_names option, and caused
issues with the install / upgrade process, when changing the lower case
table names setting *after* the install or upgrade.
With this fix, all performance schema tables are exposed with lowercase names.
As a result, the name of the performance schema table is always lowercase,
no matter how / if / when the lowercase_table_names setting if changed.
Before this fix, the performance schema file instrumentation would treat:
- a relative path to a file
- an absolute path to the same file
as two different files.
This would lead to:
- separate aggregation counters
- file leaks when a file is removed.
With this fix, a relative and absolute path are resolved to the same file instrument.
